Researchers from Stanford University have succeeded in developing a cheap plastic material that could form the basis for the development of clothing that cools the wearer, while reducing the volume of use of air conditioners.
[Translation by Dr. Nachmani Moshe]
Baterem published the research in the prestigious scientific journal Science, the researchers suggest that this new family of fabrics could in the near future become the basis for clothing that would keep people cool and chilled in hot climates without the need for air conditioners. "If you cool the person instead of cooling the building where he works or is, you can save a lot of energy," said Yi Cui, a professor in the Department of Materials Science and Engineering at Stanford University. The new material works in a way that allows the body to emit heat in two ways and make the wearer cool down by several degrees.
The material cools the body by allowing sweat to evaporate through it, a mechanism that ordinary Swedes already carry out today. However, the new material provides a second, groundbreaking cooling mechanism: it allows the heat that the body emits in the form of infrared radiation to pass through the innovative fabric. All objects, including our bodies, emit heat in the form of infrared radiation consisting of wavelengths of invisible light. For example, coats keep us warm by trapping the heat of the infrared radiation emitted by our bodies. It is this thermal radiation emitted from the body that makes us detectable in the dark by others when they use night vision goggles. "When we sit in our office, between forty and sixty percent of the heat emitted by our bodies consists of infrared radiation," says electrical engineering professor Shanhui Fan. "However, to date, almost no research has been conducted regarding the characterization of the thermal radiation properties of fabrics."
The research itself combined the fields of computer simulations, nanotechnology, photonics and chemistry in order to produce polyethylene - the same transparent and sticky plastic that we use in the kitchen to wrap sandwiches, for example, which has properties required for use as a clothing material: it allows thermal radiation, air and water vapor to pass through it and in addition - it is opaque to light seen. The most important feature was the possibility of infrared radiation to pass through the material. In the first step, the researchers used computer models to better understand the properties of porous polyethylene. The results of the models provided a wide range of possible optical wavelengths, from visible light to infrared. "By tuning a collection of parameters we were able to identify the pore size range that was best for fabric purposes, a range that was completely opaque to visible light and at the same time extremely transparent in the thermal wavelength range," said the lead researcher.
![Thermal measurements of nanopolyethylene (nanoPE) and other fabrics: left to right - bare skin, nanopolyethylene, cotton, and Tyvek [courtesy of Stanford University].](https://www.hayadan.org.il/images/content3/2017/07/hayadanarticle170717-500x370.png)
7 תגובות
June 2020. Is there anything new about this? The long-awaited refrigerator is already waiting 🙂
palm tree
The fact that infrared rays can pass through it does not necessarily mean that you can see through it with infrared. The question is whether the light comes out straight or is it refracted in many directions. This is exactly how glass works in showers in public places. You create a rough surface with glass and then, even though the glass is transparent by nature, the light that comes out of it is scattered in all directions and thus you can't really see through it.
I really hope they take care of this point before releasing the product
A welcome study and we hope it will reach the market.
But the whole story about saving air conditioning is amusing. I think they just put it in for publicity.
This species will probably be used for sports and not for clothes worn in the office. In any case, I don't think it can have a significant effect. Even if it was customary to walk around the offices without a shirt, it would not be possible to see a significant difference in electricity consumption in the summer.
A small emphasis, contrary to the title, the garment does not cool these, it just warms less than a normal garment.
Some notes
Fabric neither cools nor warms.
It is possible to lower the insulation level of a fabric (fabric, knit, etc.) by reducing its ability to maintain a warm microclimate near the skin. By various manipulations in the structure of the fiber (for example its porosity as mentioned in the article), its diameter, its surface area, the density of the fibers in the fabric, the three-dimensional structure in the fabric, the properties of the material itself and more. But the cloth is a dead substance, does not do any active action.
The technology in question is relevant to the fiber level only. Fabrics can be made from the fibers in any form known today: knitting or weaving. So the relatively small contribution of insulation in the field of infrared waves is relative to the other capabilities of the fabric obtained from the other parameters.
The apparent advantages of the new development have to meet requirements such as high radiation protection derived from the diameter of the fibers, their cross section and the knitting/weaving density, as well as the strength of the porous material and its ability to preserve certain properties under cleaning agents, abrasion in regular use and more.
A similar technology is used in insulated fibers in which activated carbon is embedded, which maintains contact with atmospheric air and allows moisture, bad odors, etc. to be absorbed.
It seems that such fabric may appear transparent to infrared cameras...
It is also important how much ultraviolet radiation the fabric blocks to prevent sun damage and skin cancer.
Some important things:
How will the fabric behave in the wash? Will the fabric lose its properties in the wash?
How will he behave in the photo? Will it be transparent in the photo or opaque?
How will it behave in water or rain?
Will the fabric be strong enough?
Will it be pleasant to use?
Do the manufacturers think that they will be able to compel consumers to go with this fabric in order to save energy?
Will the fabric be comfortable to design?
What's better than fine mesh fabric?
Please respond gently
Yehuda